Hard to discern the implication

Fascinating.

This #archaeology thread describes the “Agora Bone Well” published today by Maria Liston, Susan Rotroff & Lynn Snyder

Over 460 humans (mostly infants) & 150 dogs were thrown in the well. They tell a heartbreakingly vivid tale of all-too-ordinary life & death in ancient Athens
/1 pic.twitter.com/WBjMlQpv4X

— Flint Dibble 🍖🏺📖 (@FlintDibble) October 1, 2018

Click for the thread.

This tweet in particular raises a question I am not sure I have ever considered.

The sex ratio (basically 50/50) and gestational ages of these infants demonstrate that these deaths were mostly due to naturally high infant mortality rates in premodern societies. As Aristotle noted in his History of Animals: “most babies die before their seventh day”
/15 pic.twitter.com/HRPEGLjcl4

— Flint Dibble 🍖🏺📖 (@FlintDibble) October 1, 2018

If, in ancient times, half or more children died near birth, it introduces the idea of disjoint populations.

Today we expect, in developed nations, less than one in a hundred children born to die soon afterwards.

In Classical Greece, taking Aristotle at face value, 50 of one hundred die.

So my question is whether there is some systemic variance between those who die and those who survive? Or is it close to random selection?

More a thought exercise than anything else. It is hard to discern the implication, especially since the transition to low child mortality is so recent.